The criterion is different from his list of the greatest films in that he chose titles for their cultural significance. Included are lesser films that nevertheless attained iconic status including Carrie, The Crying Game, Easy Rider, The Exorcist, and Fight Club. Most major directors are represented by no more than a single film, intentionally.
My quibble is that the list still errs on the arty side, disregarding comedies other than older films such as Duck Soup and Some Like It Hot and action films. Excluded films like American Grafitti, Animal House, Rocky, Rambo, and Brian de Palma's Scarface are certainly more widely known and referenced in American and global culture than such art-house darlings as The Discreet Charm of the Bourgeousie and Children of Paradise.